There currently exists several access networking technologies, with most of these networking technologies utilizing different call control protocols for access. More often than not, these access technologies and access call control protocols cannot communicate among themselves due to incompatibility among the architectures of the technologies. As a result it has proven difficult to achieve interoperability as well as scalability in a multi-protocol and a multi-vendor environment in order to build a large-scale network.
At present, real-time communications services like voice and multimedia (audio, video, and data) are provided using specific networking technologies that have their own call control services. However, there is no architecture that can be used as a single common infrastructure for offering real-time services.